Scientists have learnt to "read the minds" of mice

Scientists from the Champalimaud Foundation in Portugal have proven that this is possible - at least in the case of mice. A new study published in Nature Neuroscience shows that rodent thinking strategies can be "decoded" by the smallest facial expressions.

This discovery could radically change approaches to brain research and neurodiagnostics. As the authors note, you can get as much information about a mouse's "thoughts" by its muzzle as by observing dozens of neurons.

"We were amazed: muzzle movements provide as much clues about the thinking process as neural signals," says one of the study's authors, Zachary Meinen, a research associate at the Champalimaud Foundation. - "This opens the door to non-invasive brain research. But it also raises the question of mental privacy in the age of video surveillance."

In a previous study from 2023, the team asked mice to solve a task involving choosing one of two water sources, one of which occasionally gave out a sweet reward. To get it, the mice were forced to develop choice strategies.

"We knew that the mice could use different approaches to solve the task and could identify the chosen strategy from their behaviour," explains Fanny Cazette, lead author of the study, now at CNRS and Aix-Marseille University.

But unexpectedly for the researchers, all possible strategies were simultaneously represented in the brains of the mice, even if only one was being used at a particular moment. This prompted a thought: could the same hidden strategies be seen in facial expressions?

The team synchronously recorded the mice's facial movements and neuronal activity, and then analysed the data using machine learning algorithms. The result was surprising: the mice's facial expressions reflected their thought processes as well as their brain activity.

Moreover, it turned out that different mice showed similar facial expression patterns when using the same strategies. This means that certain "thoughts" can have stereotypical facial expressions - just like emotions.

"It's like a universal language of facial expressions, only reflecting thought processes rather than feelings," said Davide Reato, co-author of the paper from the University of Aix-Marseille.

According to the authors, the results could lead to a revolution in brain research - using conventional video. This is particularly relevant to the study of neurodegenerative diseases and behavioural disorders. At the same time, however, the question is raised: how safe are such technologies in terms of privacy?

"Video is not just about capturing behaviour. It's a full-fledged window into the brain," co-author Alfonso Renart emphasises. - "And while it's scientifically exciting, we need to start discussing ethics and mental privacy protections."